H.264 encoder speed-up via joint algorithm/code-level optimization

摘要

The outstanding coding performance of H.264 comes with the cost of significantly higher complexity, making it too complex to be applied widely. This work aims at accelerating the H.264 encoder using joint algorithm/code-level optimization techniques so as to make it feasible to perform real-time encoding on a commercial personal computer. We propose a fast inter-mode decision scheme based on spatio-temporal information of neighboring macroblocks for the algorithm-level optimization. We use a commercial profiling tool to identify most time consuming modules and then apply several code-level optimization techniques, including frame-memory rearrangement, single-instruction-multiple-data (SIMD) implementations based on the Intel MMX/SSE2 instruction sets. Search mode reordering and early termination for variable block-size motion estimation, are then applied to speed up these time-critical modules. The simulation results show that our proposed joint optimization H.264 encoder achieves a speed-up factor of up to 18 compared to the reference encoder without introducing serious quality degradation.